shin ei fy2 fuzz companion build question.

[freak scene]

i am building off of the dragon fly vero layout and i dont have a 1m2 resistor so i used a 1m5.  will this affect the sound to the point that i should order some 1m2's for this build, or should that be close enough?

here is the layout:

[Yun]

if you're refering to this schematic: 

The pic that you posted doesn't work.....

If you have a 1M resistor, put 2 100K resistors in series.  I would think that the 1M5 resistor would throw off the bias, no?  It's a 300K difference, man.....

[freak scene]

yeah, i was just trying to save space.

[Yun]

This schematic just doesn't wanna let it'self be seen, man!  

Here we go:

[Mark Hammer]

I've got an original....sort of.  I bought it at a pawn shop 15 years ago, primarily because they wanted less for the pedal than it would have cost me locally to buy a case and stomp switch.  The switch and case went to a pedal for my nephew, and the disconnected board sat aimlessly for a decade or so until someone posted a schem.  When I managed to reconnect the off-board components again, I made a mistake and wired up the fuzz pot differently from what is shown in the schem posted here.  What I did was configure the pot as a kind of pan control so that the .0033 and .0022 caps each come in via the opposite outside lug and the wiper goes to the .001/10k junction.  The pot will work in either configuration, but I just found that I was able to get a broader range of fuzz intensity settings with it wired up the "wrong" way.

I really do have to measure the C536's and voltages on that board and post the info.

Note that the components between the Fuzz and Volume pots form a midscoop filter very similar to that found on the Superfuzz.  You could easily install a 2-way DPDT toggle to swap between a non-filter level-matching resistive divider and the midscoop filter the way the Superfuzz does.  You can also increase the .001uf cap to get more top and mids, or install a 50k variable resistor (pot) between the .1uf cap and ground to vary how much mid-dip is produced.

When the Fuzz control is reconfigured in the manner I described, this fuzz is VERY similar to the Mosrite Fuzz-Rite in terms of design, except the Fuzz-Rite has no scoop filter.  I'd be very curious to hear from folks who may have both units.  On the other hand, maybe I should just install a filter-defeat switch and post some samples, right?

[chaddhamilton]

I've built this twice using that vero layout and it's insane. If all i had were a 1m5, I'd use it.

rock on.

Chadd     

[Mark Hammer]

Okay.  Yanked a C536 off my board and measured the gain.  I only did one and got a value of 256.  Measuring the C536 units I had sitting in my parts bin, the highest value I found was in the high 220s and most were 200 and below.  I should try one of the lower hfe units in there and see if it makes a difference, as well as throw a DIY one together and compare their sound.

It should be a trivial matter to install a scoop/no-scoop switch between the output of the fuzz pot and the input of the volume pot.  Everything between them is simply a mid-scoop filter.  Replacing all of that with a single fixed resistor in series with the volume pot should provide a suitable level drop that matches level between the scoop and no-scoop settings.  I'm guessing that something between 27k and 39k should be about right.  If a person wanted to make that resistor terminated by a small value cap, like 4700pf or 6800pf, the switch would toggle between the normally searing splatty scooped sound and an equal-volume fuller rounded tone.  I'm hoping to do this later today, and will report back.

[Dan N]

Thanks Mark. Don't forget the letter after the number is for the range. You can see at the bottom of this pdf, it's helpful, but hardly nails it down.

http://www.nj-sunshine.com/pdf/2SC536.pdf

[Mark Hammer]

Thanks for the link to the datasheet.  As you would expect from the sheets and suffix designations, what's on the board are C536F units.  Hence the hfe readings I've gotten between around 180 and up in my parts bin, and the 256 on the board itself.

There may be some other quality of the 536 that is visible to a more trained eye on the datasheets, but in terms of gain range, these transistors clearly do not distinguish themselves from more mundane units like 2N4401, 2SC1815/945, 2N3391, BC549, etc.

[Mark Hammer]

Well, I needed to drown my sorrows at the Edmonton loss in something, so in honour of the Oilers, I'm burning a little of the midnight variety.

Just finished the scoop bypass on my FY-2 and I have 2 words: DO IT.  No, 3 words:  DO IT NOW!

Excellent mod.  Without the midscoop, it is as wooly and chewy and gnarly as you'd like a 60's fuzz to be.  Like the very best Joe Gagan fuzz, and somewhere very close to the fuzz you hear in "Over Under Sideways Down" or "Good Morning, Good Morning" (from Sgt. Pepper's), with just a bit less sizzle and more growl.  I gather from Aron's comments on the Bosstone over the years, that the .047 cap in parallel with the 100k resistor can be varied to alter treble content, so that might be another interesting mod to the circuit. 

Note that while the idea for switching from midscoop to no-scoop came from the Superfuzz, the changeover does not sound the same in this instance.  This is primarily because the scoop in the Superfuzz not only cuts the mids bt also suppresses the octaves created by the Superfuzz rectifier circuit.  In this case there is no octaving to suppress, so that defeating the scoop produces a different, and rounder, sound than the SF does.

It takes a DPDT switch wired up so that the output of the Fuzz pot goes to the switch "input" lug, and the switch "output" lug goes to the Volume pot.  In one direction the circuit is completed by a single fixed resistor, and in the other th "input" goes to the 1000pf/10k junction and the "output" lug goes to the 1000pf/15k junction.

Without the scoop, the unit is considerably louder.  I guesstimated that something in the mid-to-high 30k's might do it.  I tried 33k and the volume balance between modes was still quite off.  Seems like either 39k or maybe even 43k might be necessary.  And just to clarify something.  I remembered the unit as somewhat louder than it really is.  With the scoop on full volume is about twice as loud as bypass, but not dramatically louder than that.  I had somehow remembered it as 3 or 4 times louder than bypass.  Apologies.  Of course, it loud is what you crave, then replacing the scoop network with a 33k, or even 27k fixed resistor is just the ticket.

One interesting sidebar.  While the re-jigged Fuzz pot (where the wiper is now the output) has a little more tonal variety when the scoop is on, with the scoop off, I can't hear much variation from one side of the Fuzz pot to the other.  Not sure why that is.  The good news is that it sounds fabulous at all positions, with neck or bridge pickup.

[freak scene]

so i checked the voltages on my transistors:

Q1

C - 1.78
B - .60
E - 0

Q2

C - .007
B - .606
E - 0.000

im using the 2n5089's. 

what should i adjust the 2.2m and 1.2m resistors to in order to correct the bias on these transistors?  i know they are both pretty close to an hfe of 500.  if i switched to oc140's would this alleviate the problem.

the thing is the bias doesnt sound off, usually if the bias is off it starts gating right?  its not doing that at all.  in fact it sounds like i imagine it should just quieter. 

is there an equation i can use to calculate the value of the resistor for an acceptable bias range based off of the hfe?

[Mark Hammer]

Just for the hell of it, I made one of these last night.  Grabbed two C536 transistors (hfe around 220), dug around for all those ceramc caps cluttering my parts bins, and just wired her up following the posted schem.  Worked great the first time I fired it up.  A slight tonal difference, but that's what you get with 10% ceramic caps I guess.

I don't say this to taunt you, but rather to convince you to just make another from scratch on perfboard, veroboard or whatever (I used perf).  There is likely something wrong on the wiring that you haven't noticed because you've been "too close" to it.  Start over.  Mine only took me about 2hrs to make and that was mostly because I was gabbing with Steve Daniels for a half hour last night in the middle of it.

[freak scene]

Just for the hell of it, I made one of these last night.  Grabbed two C536 transistors (hfe around 220), dug around for all those ceramc caps cluttering my parts bins, and just wired her up following the posted schem.  Worked great the first time I fired it up.  A slight tonal difference, but that's what you get with 10% ceramic caps I guess.

I don't say this to taunt you, but rather to convince you to just make another from scratch on perfboard, veroboard or whatever (I used perf).  There is likely something wrong on the wiring that you haven't noticed because you've been "too close" to it.  Start over.  Mine only took me about 2hrs to make and that was mostly because I was gabbing with Steve Daniels for a half hour last night in the middle of it.

i have the technology, i can rebuild it...

ill give that a shot. 

one really stupid question though.  i have been trimming my vero boards and then cutting the appropriate traces according to the picture, and then putting the components in with the non copper side up.  am i getting things backward?  i have been assuming that the component side is up in the images, not the copper side.  is this correct?

[Wild Zebra]

  Yep, Component side up, copper down.  Watch your cuts!  The Shin-ei has had a couple of discussions here and many of them involve Low Volume.  I made one also from Dragonfly's vero.  A freind has had it for a while now, but it also had even or slightly less than "unity" volume.  It sounded fine, or like I expected it to sound. Just didn't have much of a signal boost. 

[brianwenz]

Hello Hello--
    Getting rid of the mid-scoop leaves us with a fuzz similar to Nightengales'  and Dan's circuit at the other thread, right?   I built one of the FY2 circuits without the mid-scoop awhile back and it's as Mark said........I liked it better, too!   Maybe it does sound "better" with lower-gain trannys???
Brian.

[freak scene]

  Yep, Component side up, copper down.  Watch your cuts!  The Shin-ei has had a couple of discussions here and many of them involve Low Volume.  I made one also from Dragonfly's vero.  A freind has had it for a while now, but it also had even or slightly less than "unity" volume.  It sounded fine, or like I expected it to sound. Just didn't have much of a signal boost. 

yes i have seen those, but it didnt appear that any of them were resolved.  drat.

[Mark Hammer]

Unless its a hardship (and I understand that for many it could be), just perf it.  Vero is a wonderful thing, but sometimes there is just too much to keep track of.  Far easier sometimes to just follow the diagram and connect the parts.  The FY-2 is simle enough that there aren't that many parts o connect.  If you manage to score some C536 units, just note that their pinout is ECB not EBC.

[freak scene]

Unless its a hardship (and I understand that for many it could be), just perf it.  Vero is a wonderful thing, but sometimes there is just too much to keep track of.  Far easier sometimes to just follow the diagram and connect the parts.  The FY-2 is simle enough that there aren't that many parts o connect.  If you manage to score some C536 units, just note that their pinout is ECB not EBC.

sorry to keep on this but i almost have it.

so was the layout done assuming that c536's were being used?  if so, then i need to switch my pinout to use an ECB transistor, this may be my problem...

[Wild Zebra]

  Hopefully someone else will chime in, but I try to help when I can, even with my limited knowledge.  To me it looks the the layout is set up for CBE trannies.  Like it says 2n3904, 2n5088/9, etc.  What trannies are you using?

[freak scene]

im using 2n5089's